1. Field of the Invention
The present invention relates to a method for protecting a password in a man-machine system, and more particularly to a password security method for protecting the password without letting a user perceive the existence of the password.
The password is employed to limit users allowed to achieve a setting operation, etc., of the man-machine system.
It is necessary for the man-machine system to provide a password security system that can secure secrecy of a password of the system to protect the system from access by unauthorized users.
2. Description of the Related Art
A cross reference related to the present invention is, for example, Japanese Patent Publication (Kokai) No. 59-32059 laid open to the public on Feb. 21, 1984.
Operating environments of primary and remote communication systems are usually set through software. For example, the communication conditions of certain communication transmitters and the operating conditions of personal computers are usually set through software.
It is necessary to protect important conditions of a system against illegal manipulation, by limiting users who are allowed to set the important conditions. To achieve this, a particular password is introduced, and unless the password is correctly entered by a user into the system, the user is not allowed to set the important conditions of the system.
In the conventional man-machine system, at a time of system start-up, a user is prompted to enter a password by displaying an instruction of, for example, "PLEASE ENTER A PASSWORD". Therefore, the user naturally knows the necessity to enter a password and also knows the timing when a password should be entered.
A password is usually a simple combination of several characters and numerals. Therefore, the necessary password can easily be found by an unauthorized user.
Accordingly, in the conventional system, an unauthorized user can try to enter a password when he is prompted by the system. If the entered password is incorrect, he can again try to enter another password. After such operations are repeated several times, he can finally find the correct password.